Could The Thames Ever Freeze Over Again?

Every winter, as the days shorten, a chill grabs hold of the air in London. People wrap up in puffer jackets, to try and keep themselves cosy. Some hardy Northerners call the locals 'softies', and spurt clichés along the lines of: "you should see real cold back where I'm from." Perhaps they're right; in reality London rarely sees more than a frozen puddle each winter. But it once did.

Between 1309 and 1814, the River Thames turned to ice at least 23 times. This wasn't just the thin ice you'll sometimes see a cursory sign warning against down your local park. This ice was thick enough to hold an entire festival atop.

They were known as frost fairs. Part winter carnival, part illegal hedonism, they actually had an incredibly pragmatic origin. The river was a massive source of income back then, when London's trade primarily came from its ports and the lack of bridges meant there were many ferryman who relied on the Thames for a living. A frozen Thames meant they were out of a job. So with quick thinking they set up the fair, charging both traders and punters access to the ice.

The hub of action usually centred on the stretch of river between London Bridge and Blackfriars. In early frost fairs there was a host of activities to draw in the crowds. Fox-hunting, bull-baiting, football matches and nine-pin bowling all took place on the ice.

For the 1814 fair, the focus was instead on food and drink. People would roast an ox over a fire — a process that took a whole 24 hours. It was worth it, as one of these animals could feed up to 800 people. Then there was the booze, and boy was there a lot of it. In something all contemporary Londoners will easily recognise, pop-ups were in vogue, especially pop-up pubs. One was the excellently named City of Moscow, to reflect the freezing conditions.

A modern day frost fair is completely out of the question. It'd never get past health and safety, and with good reason; in the frost fair of 1739 a whole swathe of ice gave way, swallowing up both tents and people.

What about the Thames freezing over at all — could that still happen? It's unlikely. Firstly, Britain isn't as cold as it used to be — hard to believe when you've got six layers on, but true. From roughly 1350-1850 the country suffered through a 'Little Ice Age'. Today temperatures are unstable due to climate change, but they're still not as consistently cold as they once were.

There's another major factor at play: London Bridge. As with so much of London's history, this phenomenon is intimately connected with the bridge. The medieval London Bridge had narrow arches to support it, and obstructive foundations. This slowed the river around the bridge and slabs of ice would form, which jammed against the bridge's wide piers. Then a sort of snowball effect (how apt) would occur, as this process repeated and quickly a solid raft of ice formed.

This is a particularly violent way for a river to turn to ice, unlike a peaceful and flat frozen lake, a frozen Thames was a jaunty beast.

Another man-made structural change to the river, also stops ice from forming. The man to blame for this one is Joseph Bazalgette. During the Victorian period the Thames became little more than a glorified open sewer, which became a danger to public health due to cholera outbreaks. Also it stunk.

To sort the mess out and clean up the river, Bazalgette built two things: new sewers and new embankments (Victoria, Albert and Chelsea). These narrowed the river meaning it now flows faster, making ice yet more difficult to form.

Not all hope is lost though, as the Thames has partially frozen over since; during the 'big freeze' of 1962-63, someone supposedly spotted a man cycling his bike across the ice near Windsor Bridge. We hate to knock a good story, but feel some nagging scepticism over this one — purely because cycling on ice is so bloody difficult. Even if it did happen, it was well upriver of London. It looks like London will never again see another frost fair — and we only have ourselves to blame.